Printing plate clamp



June 1, 1943. P, L. ToLLlsoN I lPRINTING PLATE CLAMP 2 sheets-sheet 1 Filed Nov. 28, 1941 PAUL Tau/smv, Y, 11s/oaf? n/VBERG, @IW M2M u June 1, 1943. P. L.. ToLLlsoN '2 2,320,762

PRINTING PLATE CLAMP Filed Nov. 23, 1941 zshets-sneet Patented June l, 1943 UNTTED STATES PATENT OFFICE'.

PRINTING PLATE CLAMP `Paul L. Tollison, Nort Tornberg, Plainfield, Newspaper Machiner h Plainfield, and Isidor N. y Corporation, PlainiielrL J., assignors to Wood N. J., a corporation of Virginia Application November 28, 1941, Serial No. 420,878 7 Claims. (Cl. lill-378) This invention relates to a clamp for holding a plate down on a printing cylinder at the longitudnal edges of the plate, having particular reference to the structure of the margin bar for this purpose.

'Ihe present invention is an improvement on the margin bar disclosed and claimed in the patent to Wood, No. 1,928,161, of September 26, 1933, which patent is owned by the assignee oi the present application.

The margin bar disclosed in said Wood patent is particularly applicable where single page plates are used, whereas the margin bar of the present application is particularly adaptable for use with double page plates. Since the double page plate is much wider there is more tendency to lift When the press is running at speed and that is one reason for the utilization of the special margin bar of the present application which will hold down the center section of the wide double page f plate and would provide much better structure for use with double page plates than the margin bar of the Wood patent above noted.

The usual plate cylinder is four pages Wide and four individual plates are locked on each side' of the cylinder making eight plates in all. The showing in the present application indicates only half a cylinder and with two double page plates mounted thereon. It will be understood, of

course, that these plates might be single page plates, the showing however being of plates.

In the present invention grooves or recesses are provided in the margin bar to accommodate lips cast on a double Width page. Of course, they could be utilized in connection with lips cast on a single width page. They are shown, however, merely with double width pages. One of the reasons for having two lips on the plate and the particular construction shown is to guard against having a portion of the lip which passes under the margin bar from being damaged. If the lip were made the full length of the plate, or, the margin bar recess was longer than the lip on the plate and covered it completely, any damage to the plate lip might possibly cause dimculty in sliding it into the recess into the margin bar. Furthermore, the center of the margin bar is made solid so that when single page plates are used a solid surface is provided for a single page plate to bear against. If the grooves or recesses on the margin bar carried the full length of the margin bar then there might be a tendency for single page plates to be cut oy the sharp edge of the margin bar.

double page The principal objects of the invention are to hold down the straight edges of the plate and prevent their bulging out so as to imprint an excessively black impression on the paper, and also to avoid the possibility of breakage of the edge of the plate due to its pounding back and forth repeatedly, and to provide a construction by which when the attendant pulls his end clamps too tight it will not cause the bowing of the edges of the plate.

Other objects and advantages of the invention will appear hereinafter.

In the accompanying drawings:

Fig. 1 is a plan of a printing cylinder showing the present invention in use;

Fig. 2 is a fragmentary view of the plates with the margin bar in position;

Fig. 3 is a lsectional view on the line 3 3 of Fig. 1; Y

Fig. 4 is an end view on the line 4 4 of Fig. l, the cylinder being shown in section; and

Fig. 5 is a disassembled perspective view of the parts.

In clamping stereotype plates on printing press cylinders it is customary to secure them by longitudinal sliding clips carrying beveled edges to t complementary beveled edges on the stereotype plates. AWith slow running presses this form of clamping has been sufficient to hold the plates properly in position, but with the advent of high speed printing presses there is a tendency on the part of the center of the edge of the plate to bow out under speed. The repetition of this action of pressing the edges of the plates back against the cylinder as they pass through the impression, then throwing them out by centrifugal force, results in fatigue of the metal and sometimes a piece breaks out of the edge of the plate. This is apt to cause considerable damage. Besides the centrifugal action just described, the bowing out of the edges of the plates is apt to be caused or increased by the setting in of the clamps on both ends of the plate. The natural tendency of an operator working on a high speed press is to keep pulling his clamps tighter so that the plate will not fly off, thus accentuating the bowing outwardly of the edges of the plate.

As in the patent hereinbefore noted one of the purposes of the present invention is to provide a clamp which will hold down the edge of the plate which is parallel to the circular axis of the printing cylinder and to do it in such a manner that the plate will not be subjected to unnatural strains as it grows in length circumferentially under repeated impressions.

In the present invention each plate I in addition to its holding means at its semi-circular ends, is provided with tongues or projections I I, I2 spaced apart on the edge of the plate, that is, on the straight edge of the plate, preferably at about mid-way of the ends. The margin bar I3 is provided with grooves or recesses I4 and I5 into which grooves fit the tongues or projections Il and I2; that is, the tongues or projections II and I2 extend into the grooves I4 and I5 of the margin bar. The margin bars I3 are of less length than the plates and the object vof making them shorter is to permita pressman to lift the plate by its straight edges which it would be somewhat diicult to do if such bars were of full length. The spaced apart tongues or projections II and I2 are shown as of considerable length and they have considerable clearance in the grooves or recesses I4 and I5 of the margin bar I3 so that the plates will be firmly held at the longitudinal edges against the cylinder. The margin, bars-obviously 4are u sed in addition to the clamping means and the center; clips I5` and `margin rings ordinarily employed. The margin bars'are secured to the cylinder by means of screws I6 as 'shown or in any other preferred manner. y v

Having thus fully described our invention what we claim as new and desire to secure by Letters Patent of the United States is:

1. The combination with a printing plate Icylinder, of printing plates, each of said plates being provided on its straight longitudinal edge with a plurality of spaced aparttongues, a margin bar rigidly secured to s aid plate cylinder and having a plurality of spaced apart-,grooves for the reception of the tongues on the edge of the plate, to thereby hold the straightV edge jof the plate against the cylinder and to provide' fiat bearing surfaces for a straight edge plate and means for clamping the curved. edges of the plates on the cylinder.

2. The combination of a substantially semicylindrical stereotype .printing plate having a plurality of Yspaced `apart tongues along its straight edge, and a plate cylinder, a margin bar rigidly secured to said plate cylinder and provided with a plurality of spaced apart grooves into which the tongues of the plate project thereby holding the straight edge of the plate against the cylinder, said bar providing clearance between Vthe plate and bar and flat bearing surfaces for a straight edge plate with means for clamping the curved edges ofthe plate.

Y V3. The combination with Va printing' plate cylinder, of a margin bar extending longitudinally thereof provided with spaced apart grooves along the length of the bar, a substantially semicylindrical stereotype printing plate on each side thereof, each printing plate having substantially tangential spaced apart tongues arranged along the length of the bar adapted to project into said spaced apart grooves and thereby restrain bowing of the plates while running, said grooves providing circumferential clearance between the plate and the clamping bar, said bar providing flat bearing surfaces for a straight edge plate, and means for clamping the curved edges of the plate on the cylinder.

4. The combination with a printing plate cylinder, of a margin bar extending longitudinally thereof, said margin bar being provided with a plurality of spaced apart grooves on its opposite edges extending along the length of the bar, a substantially semi-cylindrical stereotype printing plate provided with a plurality of spaced apart tongues along its,` straight edge, said tongues adapted to project into said recesses and restrain bowing of the plate' while running, said bar providing at bearing surfaces for a straight edge plate, and means for clamping the curved edges of the plate on the cylinder.

5. The combination with a printing plate cylinder, of a margin bar thereon extending longitudinally and having a plurality of grooves on opposite edges thereof, a printing plate on each side thereof, each printing plate having a plurality of tongues extending along the edge of the plate adapted to extend into saidgroovesv and serving to restrain the straight edges of the plate from buckling, said bar providing flat bearing surfaces for a straight edge plate. A

(i. The combination with a` printing plate cylinder, of a margin `bar thereon extending longitudinally and having a plurality of spaced apart grooves on opposite sides thereof, a printing plate on each side thereof, each printing plate having a plurality of spaced` apart tongues extending along the edge of the plate adapted to extend into saidgrooves and servingto restrain the straight edges of the plate from buckling, said bar providing flat bearing surfaces for a straight edge plate.

7. As an article of manufacture a margin bar for holding down the straight edges of substantially cylindrical printing plates, said margin bar being formed with spaced apart grooves on its opposite sides, an unbroken portion of the bar separating said grooves.

PAUL L. TOLLISON. ISIDOR TORNBERG. 

